This invention relates to lenticular lens processes, and more particularly, to a method of producing very high quality interlaced image plots having exceptionally sharp, smooth type and line edges for conveying various desired visual effects when the image plots are printed and subsequently viewed through a properly positioned and aligned sheet of lenticular lens material.
Lenticular lens processes are well-known in the art. In commercial applications, for example, they are used to produce advertisement or promotional materials including graphic images and textual materials (it being appreciated that textual materials can also be considered as graphic images). Although there are a number of visual effects which can be created using lenticular lens processes, the most common effect is one in which a first image appears as a piece of lenticular lens is held at one angle, but a second and different image appears if the piece is held at a different angle. As described hereinafter, the images are generally referred to as "interlaced" images; that is, the respective images are divided into respective strips or segments with the segments of one image then being arranged between adjacent segments of the other image. The rearranged images are then viewed through a sheet of the lenticular lens material. Such a sheet is typically flat on one side, this flat side being fitted over the rearranged images. The other side of the sheet typically has a series of half cylindrical (convex) shaped lenses formed on it, each lens typically extending linearly along one side of the sheet, parallel to the respective image segments, and parallel to the other lenses formed on the sheet. The spacing between adjacent lens' segments may vary from one sheet to another, and the number of lens' segments formed on a particular sheet is generally referred to as lenses or lenticules per inch, or LPI.
It is known that images which are interlaced may be the same image photographed from different angles. This was originally accomplished using a stereographic camera which exposed the same object or scene through slit-like gratings. The resulting photograph of the object or scene comprised interlaced slices of the image exposed onto the same sheet of film. A problem with this technique was the requirement to recreate the object in such a manner that everything surrounding the object remained perfectly still and motionless during the time it took to produce the multiple images of the object. It was difficult to incorporate textual material in the final product using this approach. Also, this process was limited in that while it could produce "flip" images, and could also provide an illusion of depth, it could not produce many of the desired effects available today. These effects include "apparent" motion, zooming in or out, transformation ("morphing") of one image into another, and more sophisticated simulation of depth; i.e., three-dimensionalor 3D effects.
With the introduction of silver based film lithography and contact processes, it became possible to make separate images of an object on separate sheets of film. Now, with the use of slit-like masks and proper registration, these multiple contact exposures could be interlaced so two or more images were merged onto one sheet of film. While processes developed using silver based film addressed some of the drawbacks of the stereographic techniques, these and other lenticular processes are time consuming, relatively expensive, and still do not allow for ready merging of more than one effect onto the same set of interlaced films.
Development of improvements to lenticular processes is on-going. In U.S. Pat. No. 5,488,541, for example, there is described a method for producing multidimensional lithographic separations free of moire interference. According to the process, non-binary pixels forming an image are converted to separate color plates prior to the images being interlaced and a film of the interlaced images being plotted. The process makes use of first order stochastic screening in which all of the printed dots comprising an image are of the same size (diameter). These dots are placed in a non-matrix arrangement such that the number of dots in any area of the image produces a variation (shade) in the solid color produced when an area is solidly filled with dots of the same color. Absence of color results when no dots are present in an area. It is a drawback of this process that it does not use the full resolution capabilities of film plotters now commonly in use for prepress or graphic arts material.
U.S. Reissue Pat. No. 35,029 to Sandor, et al., teaches a method of preparing three-dimensional autostereoscopic images of an object. The method teaches incorporating side perspectives of the object, and utilizes a preferred printing direction. More than two different views of the objects must be interlaced in order to distinguish the object from a binocular or stereoscopic image of it.
Continuing and common disadvantages of these and previous processes include such matters as the resolution of images in pixelized or bitmap forms with the textual material and lines composed of noticeable blocks. In addition, there are stair steps or "jaggies" on the edges of images which detracts from the sharpness and crispness of a final image when viewed through a lenticular material.